1. Technical Field
The present disclosure relates to a field device whose software is replaced through a field bus and a field device software update system using the field device and, more particularly, relates to implementation of history information management of software.
2. Related Art
In recent years, in order to improve function distribution intended for process improvement, in a process control system of industrial automation, an additional function such as expansion of a self-diagnosis function has also been demanded for a field device including a sensor (e.g., a flowmeter or a thermometer), an actuator, and a controller making up a control loop of feedback control. Since a conventional field device has rich functions and thus a bug is likely to occur, software or firmware installed in the field device is replaced (updated) using the communication function of a field bus (see e.g., JP-A-2005-173747).
FIG. 7 is a block diagram to show a configuration example of a field device and a process control system using the field device in a related art. In FIG. 7, a field device 1 incorporating an analog input function block AI and a PID function block PID is connected to a field bus 2 for FOUNDATION Fieldbus (registered trademark), serial transmission or the like. Plural field devices (not shown) are connected to the field bus 2.
The field device 1 is made up of a sensor 11 for measuring a process amount, a communication section 12 for conducting data communications with a different field device or any other device through the field bus 2, a computation control section 13 for controlling the functions of the field device 1 and replacing software or firmware, and a storage section 14 having program storage areas 14A and 14B for storing software, firmware or a program of a computation portion for converting a measurement signal from the sensor into an output signal.
Software of the field device 1 can be replaced with new software to upgrade the function of the existing software or solve a problem.
Any other field device (not shown) is connected to the field bus 2 and a host 3 is connected to the field bus 2 through an I/O unit and a bus (not shown). The host 3 is a host system of DCS, including software transfer means for downloading or transferring software to a field device.
In the configuration, the field device 1 receives data of new software from the host 3 through the field bus 2 and stores the received new software in the storage area 14B where operating software is not stored.
After the data is downloaded, the field device 1 is restarted and operates the new software stored in the storage area 14B. This means that the operating software is rewritten in the field device 1.
Thus, in the related-art field device, the software or firmware installed in the field device can be replaced using the communication function of the field bus.
However, in the related-art field device, history information as to what revision the software which previously operated has undergone cannot be known although software can be replaced.
Also, in the related-art field device, the revision of the software which previously operated cannot be grasped and thus it is hard to restore the operation of the field device to the operation of the previous revision software if a defect occurs.
Further, in the related-art field device, the revision of the software which previously operated cannot be grasped and thus the circumstances and the progress of a plurality of software products installed so far are not known and the defects of the software which occurred in the past cannot be investigated.
Further, in the related-art field device, the revision of the software which previously operated cannot be grasped and thus if a defect occurs, it is not easy to restore the operation of the field device to the operation of the previous revision software. Accordingly, it takes time in maintenance of the software, and the whole process control system is affected.